Modern data centers often include thousands of hosts that operate collectively to service requests from even larger numbers of remote clients. During operation, components of these data centers can product significant volumes of machine-generated data. In order to reduce the size of the data, it is typically pre-processed before it is stored. In some instances, the pre-processing includes extracting and storing some of the data, but discarding the remainder of the data. Although this may save storage space in the short term, it can be undesirable in the longer term. For example, if the discarded data is later determined to be of use, it may no longer be available.